content: /* ===========================================================
   * JFreeChart : a free chart library for the Java(tm) platform
   * ===========================================================
   *
   * (C) Copyright 2000-2011, by Object Refinery Limited and Contributors.
   *
   * Project Info:  http://www.jfree.org/jfreechart/index.html
   *
   * This library is free software; you can redistribute it and/or modify it
   * under the terms of the GNU Lesser General Public License as published by
   * the Free Software Foundation; either version 2.1 of the License, or
   * (at your option) any later version.
   *
   * This library is distributed in the hope that it will be useful, but
   * WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY
   * or FITNESS FOR A PARTICULAR PURPOSE. See the GNU Lesser General Public
   * License for more details.
   *
   * You should have received a copy of the GNU Lesser General Public
   * License along with this library; if not, write to the Free Software
   * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301,
   * USA.
   *
   * [Oracle and Java are registered trademarks of Oracle and/or its affiliates.
   * Other names may be trademarks of their respective owners.]
   *
   * --------------------
   * PowerFunction2D.java
   * --------------------
   * (C) Copyright 2002-2009, by Object Refinery Limited.
   *
   * Original Author:  David Gilbert (for Object Refinery Limited);
   * Contributor(s):   -;
   *
   * Changes:
   * --------
   * 01-Oct-2002 : Version 1 (DG);
   * 28-May-2009 : Added accessor methods for co-efficients, implemented
   *               equals() and hashCode(), and added Serialization support (DG);
   *
   */
  
  package org.jfree.data.function;
  
  import java.io.Serializable;
  import org.jfree.chart.HashUtilities;
  
  /**
   * A function of the form y = a * x ^ b.
   */
  public class PowerFunction2D implements Function2D, Serializable {
  
      /** The 'a' coefficient. */
      private double a;
  
      /** The 'b' coefficient. */
      private double b;
  
      /**
       * Creates a new power function.
       *
       * @param a  the 'a' coefficient.
       * @param b  the 'b' coefficient.
       */
      public PowerFunction2D(double a, double b) {
          this.a = a;
          this.b = b;
      }
  
      /**
       * Returns the 'a' coefficient that was specified in the constructor.
       *
       * @return The 'a' coefficient.
       *
       * @since 1.0.14
       */
      public double getA() {
          return this.a;
      }
  
      /**
       * Returns the 'b' coefficient that was specified in the constructor.
       *
       * @return The 'b' coefficient.
       *
       * @since 1.0.14
       */
      public double getB() {
          return this.b;
      }
  
      /**
       * Returns the value of the function for a given input ('x').
       *
       * @param x  the x-value.
       *
       * @return The value.
       */
      @Override
      public double getValue(double x) {
          return this.a * Math.pow(x, this.b);
      }
  
      /**
       * Tests this function for equality with an arbitrary object.
       *
       * @param obj  the object (<code>null</code> permitted).
       *
       * @return A boolean.
       */
      @Override
      public boolean equals(Object obj) {
          if (!(obj instanceof PowerFunction2D)) {
              return false;
          }
          PowerFunction2D that = (PowerFunction2D) obj;
          if (this.a != that.a) {
              return false;
          }
          if (this.b != that.b) {
              return false;
          }
          return true;
      }
  
      /**
       * Returns a hash code for this instance.
       *
       * @return A hash code.
       */
      @Override
      public int hashCode() {
          int result = 29;
          result = HashUtilities.hashCode(result, this.a);
          result = HashUtilities.hashCode(result, this.b);
          return result;
      }
  
  }
  